Table 2.
Performance of natural biodegradable polymers in ligament/tendon TE
| Material | Scaffold | Application | In vivo/in vitro | Mechanical response | Biological response | Refs. | |||
|---|---|---|---|---|---|---|---|---|---|
| Young’s modulus (MPa) | Stiffness (N/mm) | Max. strength (MPa) | Max. loada (N) | ||||||
| Collagen | Aligned parallel 200 extruded-crosslinked col fibers; coating with Col | Ligament | In vitro (ACL and PT fibroblasts) | ND | ND |
Cells adhesion, proliferation ACL cells: ovoid shape; no alignment; PT cells: elongation |
[46] | ||
| Aligned parallel 200 extruded-crosslinked Col fibers | In vivo, rabbit model | ND | ND | Skin/ACL fibroblasts survived 4-6 weeks, after implantation; scaffold resorption after 8 weeks | [47] | ||||
|
(i) Extruded-crosslinked Col fibers from bovine Achilles tendon (ii) Extruded-crosslinked Col fibers from rat tail tendon (iii) Fiber-embedded gel scaffolds |
In vitro (fibroblasts) |
(i) 359.6± 28.4 (ii) 995.1 ± 144 (iii) 83.4 ± 10.8 |
ND |
(i) 36.0 ± 5.40 (ii) 106.1 ± 13.90 (iii) 5.4 ± 0.4 |
ND | Non-uniform cells distribution | [45] | ||
| Braid-twist scaffold of extruded-crosslinked Col fiber i) with or ii) without gelatin | In vitro (primary rat ligament fibroblasts) |
(i) 6.32 ± 0.95 (ii) 148 ± 170 |
ND |
(i) 1.07 ± 0.06 (ii) 19.3 ± 3.10 |
ND | Cell adhesion, proliferation; only (ii) exhibited increased cellular activity after 21 days of culture | [48] | ||
| Woven scaffold by electrochemically aligned Col threads (yarns) | Tendon/tendon | In vitro (MSCs) | ~ 520 | ND | ~ 65 | ND |
MSCs adhesion, proliferation, elongation after 35 days in culture Tendon-specific/related markers |
[62] | |
|
Sponges (L/W/T = 23/9/3 mm) i) Non-stimulated scaffolds ii) Mechanically stimulated scaffolds |
In vitro (rabbit MSCs)/In vivo, rabbit model |
(i) 343.2 ± 21.2 (ii) 441.2 ± 26.3 |
ND |
(i) 50.2 ± 9.2 (ii) 72.1 ± 11.1 |
(i) 271.5 ± 17.5 (ii) 339 ± 11.4 |
MSCs adhesion and alignment (i) and (ii) excellent cellular alignment, after 12 weeks of culture Tendon-related ECM components |
[63] | ||
| Silk | Knitted microporous silk mesh rolled up around a braided silk cord | Ligament/ligament | In vitro (MSCs)/in vivo, pig model | ND | 58.5 ± 17 | ND | 398 ± 70 |
MSCs adhesion, proliferation, differentiation Ligament-specific ECM markers at 24 weeks post-operatively |
[50] |
|
Wire rope–like scaffolds (i) Cell seeded-scaffold (ii) Non-seeded scaffold |
In vivo (autologous stem cells), sheep model | ND | 194 ± 27 | ND | 1450 ± 65 |
(i) Higher cell content in the inner part, after 6 months (i), (ii) Silk fiber degradation after 12 months |
[53] | ||
|
(i) Wire rope of multifiber (ii) Parallel multifiber (theoretical) |
In vitro (BMSCs) | ND |
(i) 354 ± 26 (ii) 1740 |
ND |
(i) 2337 ± 72 (ii) 2214 |
(i) BMSCs adhesion, proliferation, differentiation Ligament-specific markers, after 14 days of culture (ii) ND |
[16] | ||
|
Knitted silk mesh integrated: (i) Aligned electrospun fibers (ii) Random electrospun fibers (iii) Without fibers |
In vitro (MSCs) | ND |
(i) 22.12 ± 1.2 (ii) 19.21 ± 0.9 (iii) 16.24 ± 0.8 |
ND |
(i) 129 ± 7.4 (ii) 106 ± 6.2 (iii) 93.2 ± 5.6 |
(i) MSCs proliferation, elongation, orientation along the fibers; ligament-related proteins increased when compared to (ii) scaffolds | [51] | ||
| Microporous silk sponges incorporated into a knitted silk scaffold | In vitro (BMSCs and ACL fibroblasts)/in vivo, rabbit model | ND | ND | BMSCs with higher proliferation, ligament-related ECM markers and in vivo viability, comparing to ACL fibroblasts | [56] | ||||
| In vitro (MSCs) | ND | 50 ± 4 (after 14 days of cell culture) | ND | 257 ± 7 (after 14 days of cell culture) |
MSCs adhesion, proliferation Ligament-specific ECM markers, after 15 days of culture |
[64] | |||
|
(i) Wired (ii) Braided |
In vitro (hFFb) | ND |
(i) ~ 280 (ii) ~ 240 (wet) |
ND |
(i) ~ 1560 (ii) ~ 1610 (wet) |
Inconclusive cell invasion, proliferation | [65] | ||
|
(i) Silk (ii) PBS |
Extruded fibers in knitted scaffolds (weft knitting) | Tendon/ligament | In vitro (L929 fibroblasts) |
(i) 31.6 (ii) 7.9 |
ND |
(i) 17.4 (ii) 8.2 |
ND |
(i), (ii): L929 adhesion, proliferation (i) Differentiation, after 14 days of culture; (ii) cells with rounder shape |
[66] |
| HA (HYAFF 11®) | Multilayered knitted cylindrical array of fibers | Ligament | In vitro (MSCs) | ND | ND |
MSCs adhesion, proliferation, differentiation Ligament-specific ECM markers |
[43] | ||
amaximum tensile load (max. load); bhuman foreskin fibroblasts (hFF)